Disrupted interoception by auditory distractor: Difficulty inferring the internal bodily states?

Perception of internal bodily sensations or interoception has recently been studied under a predictive coding framework. In this framework, the brain utilizes both top-down prediction and bottom-up prediction error signals to determine the content of the perception through inferences regarding the cause of the ongoing sensation. Particularly, interoception and other exteroceptive sensory modalities are considered to share an integrated, intertwined process of inference. Thus, it is possible that exteroceptive stimuli interfere with the inference of interoception. Hence, we investigated whether auditory stimuli disrupted interoceptive inference that resulted in diminished awareness of interoception. Thirty healthy volunteers performed the heartbeat counting task with and without distractor sounds. The psychophysiological traits that would reflect the individual differences in prior prediction signals of interoception were measured as the high-frequency component of the heart rate variability (HF-HRV) at rest and trait interoceptive sensibility. The results showed that the auditory distractor diminished objective interoceptive accuracy, subjective confidence in interoception, and the intensity of the heartbeat, suggesting disrupted interoceptive inference under external stimuli. Importantly, individual differences in the distractor effect were modulated by both the HF-HRV and tendency to worry about bodily states. These findings support and extend the predictive coding account of interoception by suggesting that interoceptive inference could be disrupted by external stimuli and that such disruption may be modulated by a difference in prior predictions and its precision regarding interoception.